Download Some introductory definitions to keep in mind:

Some introductory definitions to keep in mind:
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Electricity – Electricity is something we often take for granted, but are never really able to concretely
understand or define. For our purposes, the best definition of electricity is the movement of electrons
from one place to another. Usually these electrons will move in a circular path (called a circuit.) The
only real exception to this circular path idea is static electricity (lighting, static electric shocks, etc.)
Voltage – Voltage simply put, is electric pressure. More specifically, voltage is the measure of
electricity’s ability to overcome obstacles in its path. The higher the voltage, the easier it can overcome
obstacles.
Resistance – The obstacles that we’re talking about are defined by their resistance. Resistance is the
measure of how much opposition to electrical flow an object has. Copper wires usually have very little
resistance, and thus, does not obstruct the flow of electricity. These are called conductors. Other
materials, like carbon or water, have higher resistances and restrict the amount of electricity that can
flow through them. Materials that let little or no current flow through them are called insulators.
Examples of such materials are rubber, plastic, and ceramics.
Current – This brings us to a discussion of electrical Current. In order to understand Current, we must
remember that electricity is the flow of electrons in a circuit. Current is the measure of this flow – it is
defined as the number of electrons that pass a given point in the circuit over the time of one second.
Thus, one Ampere (or Amp), the unit of current flow, is equal to 6.24x1018
(6,240,000,000,000,000,000) electrons per second.
Ohm’s Law – Ohms Law is the mathematical formula that relates Voltage, Current, and Resistance. It’s
very useful even with simple circuits.
o Voltage  Current  Resistance
Power – Power is the measure of the actual amount of work that electricity can do. For instance, a light
bulb uses a certain amount of power, measured in Watts. Watts are the unit of power used for electrical
measurements. Mathematically speaking, Power is found by multiplying voltage times current.
o Power  Voltage  Current
Term
Voltage
Current
Resistance
Power
Electrical Terms Summary
Abbreviation
Unit
V
Volts
I
Ampere
R
Ohms
P
Watts
Abbreviation
V
A
Ω
W
Remember that when we talk about units, its just like in everyday life: Water is measured in gallons, car
engines are measured in horsepower, distance is measured in miles, and weight is measured in pounds.
Similarly, voltage is measured in volts, current in amperes, resistance in ohms, and so and and so forth.